Ruminations on Bolger's Storm Petrel

Discussion in 'Boat Design' started by cluttonfred, Apr 9, 2014.

  1. cluttonfred
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    cluttonfred Junior Member

    Hello, all. I have had plans for Phil Bolger's Storm Petrel for many years, and recent discussions of Frank Dye's small boat adventures in his Wayfarer dinghy prompted me to dust them off again and take another look.

    For those not familiar with the design, Storm Petrel (#337 16'4" x 5'2") is basically a flat-bottom plywood skiff with a 3/8" steel plate full keel for both lateral area and ballast. The decked middle section and side benches are watertight to keep stores dry and even shelter the crew in a pinch with enough foam flotation to sail fully-flooded, while the footwell and bow area are free-flooding and self-draining. The sail area is modest with the understanding that it's a boat for going places and if there's little wind you'll use the motor.

    What are the pros and cons of a design like this one? I have often thought that the box-top hatch was not ideal and a conventional trunk cabin (like the spritsail sloop version pictured below) or a spray-hood-shaped top with a hatch at about a 45-degree angle (like my old sketch below) would be more practical and safer if you needed to open the hatch in rough water.

    Other thoughts?

    LINKS (the first one is the designer's description)

    http://www.belljar.net/petrel.htm
    http://www.belljar.net/bolgersp.htm
    http://www.boats.backwater.org/StormPetrel/
    https://www.flickr.com/photos/hallman/tags/stormpetrel/

    Cheers,

    Matthew
     

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  2. Petros
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    Petros Senior Member

    I like it. but I can never leave well enough alone, I would be tempted to put a more modern dagger board keel on it, and perhaps raise the whole forward deck area to increase cuddy volumn since it seems to me that deck area up front is not very useful anyway.

    I would also consider a conventional sloop rig as well.
     
  3. cluttonfred
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    cluttonfred Junior Member

    Thanks, Petros. It's funny, the things you suggest changing are exactly the features that attract me to the design in the first place.

    The shallow steel ballast keel is what distinguishes Storm Petrel from almost every other small sailboat with center/dagger/leeboard lateral area and provides the self-righting capability and stability even if flooded.

    The simple, reefable rig is perfect for low-stress sailing anywhere where more wind is the order of the day.

    I actually thought of replacing the high box-top hatch with an ordinary low one, strong enough to walk on, to free up deck space, but decided against it because of the storm shelter scenario and ventilation of the enclosed spaces generally. As shown, it looks like the hatch could be made to hinge forward for access and then dog down tight, with a couple of small cleats for simple lashings if you ever had to do so from inside.

    On ventilation, I would think that the boat would last longer with some sort of vents forward and at the aft end of each bench, but they would need to close up water- and air-tight when underway to maintain the "inverted bottle" effect and keep water out if knocked completely over.

    Different strokes....

    ;-)
     
  4. SukiSolo
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    SukiSolo Senior Member

    I knew a guy who did very similar voyages to Frank Dye but in a Mirror 16. Try stuff like Scotland to Denmark etc all singlehanded so do not ignore that type of craft. Surprisingly seaworthy IMHO a better boat than the Wayfarer. He did have a special folding frame device, similar to a cockpit spray dodger, which he fitted to allow him to cook at sea in roughish weather. Also to keep the boat drier. Note the Mirror has a double floor, self drain type construction so ample flotation, yet lighter than the Wayfarer.

    If I look at modern equivalent boats, I'm not sure a Laser Stratos or Bahia could do that kind of sea voyaging as well. It would be more along Drascombe Lugger types that could do it. Worth checking those out as they are more similar in style to the Bolger but probably better suited. They do actually sail OK, and are well balanced.
     
  5. Skyak
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    Skyak Senior Member


    I am a Bolger fan but I have never seen this design before and I fail to see the brilliance. It's very simple and sturdy, but at 8 sheets far from efficient. The plate keel gets support from the severe rocker, but that rocker also results in great waste of the rectangular blank. I am with Petro, a dagger with a bulb would give more performance in more conditions with about the same work and less material. I love tough little cruisers, but the open bow, bulwarks, and deep, non-draining cockpit are all wrong. You can't go below to ride out a storm, the boat will fill with water. The standard sport boat bubble deck and self draining open cockpit would be far safer and lighter while providing twice the usable interior. Bulwarks and open sections make it look inviting to go forward, but why would you go forward other than to bail? I even disagree that the lanteen sail is easy to reef -a dipping lug is better and a sloop is more versitile -reefing and hove to. For a sturdy simple boat this size I would start with the CS17 and add water ballast/self draining to cockpit to make it equivalent righting.
     
  6. cluttonfred
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    cluttonfred Junior Member

    I guess we're going to have to agree to disagree on this one, Skyak. Eight sheets of 3/8" plywood does seem like not a lot to me for a 16' decked boat with a watertight 6' 6" long shelter cabin.

    I don't see the efficient use of the steel plate as an issue--you can use the leftovers for the tabs and some backing plates, maybe weld up bow and stern eyes. A 4' x 8' sheet of 3/8" in rolled steel should run under $400 (if you want to cut the keel out in two halves) and it might be possible to get the keep out of a smaller piece, I'd have to sketch it out. A daggerboard with bulb might be more efficient but it would be more work to make and use, and more worry of grounding out and snagging lobster traps, etc.

    You certainly can go below to ride out a storm--that's one of the key features of the design--as it is designed to be completely stable with the cockpit flooded and the forward well self-draining.

    Being not at all interested in dinghy racing I am not bothered by the lateen sail--it looks handy to me for medium to high winds. I would probably adapt a small spinnaker (I once saw one on a Optimist pram) for improved downwind performance in light air. Upwind in light air I'd use the motor.

    I do agree that the cockpit is odd and one change that I would consider is adding a watertight floor just above the waterline and scuppers to make that self-draining as well. That would mess up the flooded stability a little by adding flotation down low, but I think I could live with that. You could even add a plug to be able to flood the new compartment under the cockpit floor in an emergency if needed.

    Different strokes....
     
  7. Petros
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    Petros Senior Member

    the sloop rig is more efficient and adjustable for various conditions and has less members (booms/yards, etc) than the lateen. It will allow you to point higher which can be critical when trying to get some distance from a lee shore, not just for racing.

    If you want an easy to handle rig why not consider a junk rig: it will not flog, is efficient in all wind conditions, is self tacking and easy to raise/lower when on the water.

    And frankly the lateen rig sucks, at least in my experience. after spending years in simple sloops I tried one and I could not get it to perform well, and its limited ability to trim it was not a benefit at all.

    A simple dagger board would also be more efficient, could give you better righting moment with a small bulb, and can be pulled all they way up when you want to row it or beach it. That low aspect ratio slab of a keel is really one of the most obsolete aspect about the design.

    If you have a lot of nostalgia for old inefficient "traditional" designs, have at it. You will also have to love dealing with its performance short comings, and I hope you enjoy the nostalgia of that as well.

    I am just telling you if I was going to the trouble of building a boat, I would keep the classic design but modernize certain aspects of it to improve the performance and make sailing it more enjoyable (rather than an exercise in "nostalgia" sailing). the more pleasant it is to sail it, the more it will get used.
     
  8. cluttonfred
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    cluttonfred Junior Member

    Interesting commments, Petros, though they seem to come from more of a racing point of view than a cruising or just "messing about" one. Absolute performance is not the only measure of a boat's worth, especially a homebuilt boat. Ease and cost of building, ease of use, durability all play a part. I am not an experienced sailor, but I have built several of these Bolger plywood boats over the years including my first Brick punt (featured in Bolger's NYT obit), a Yellow Leaf canoe, a June Bug skiff and a Tortoise that never made it to the water because we painted it black and white with gunports and kids used it as a pirate ship in the yard. I can say from experience that his simple designs perform better than most folks might think without the benefit of trying one, and even when the performance is modest, fun is not always measured by the knot. I am not saying that something like Storm Petrel is the perfect boat for everyone, but neither should it be dismissed out of hand because it won't point or ghost with a racing dinghy.
     
  9. Skyak
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    Skyak Senior Member

    I certainly don't want you to agree just to agree. You are asking about a design for severe life threatening conditions -what would I be if I didn't point out problems?. If you have any expectation of operating in those conditions you should consider the reasoning I offer and draw your own conclusions. Grounding is a great reason to use this plate keel and if you sail somewhere that hard groundings are common the plate is much better than the dagger.

    I don't trust 'flooded stability'. In my experience things that float low roll in waves their size and greater and it doesn't take much rolling to beat up occupants and take on water (this design has a single unsegmented float chamber and will sink flooded). You can demonstrate this in a bathtub with a scale model. Light self draining things are free to float up and slide off waves. A buoyant arched cabin also cuts upside-down stability and the higher the cabin the greater the ultimate stability.

    Nothing I have said is aimed at racing. Performance is important to safety and there are many things you can do to improve safety/stability that cost a little performance -so I always want to maximize my performance budget and spend it wisely.

    Spinnakers are not compatible with lanteen rigs -the mast is too short.

    This design does not look like it was intended to include an outboard. The rocker is too great aft, the hull is flat forward, the flooded stability plan doesn't fit. If an outboard is critical to the capabilities of your boat you should chose a design that plans for it.
     
  10. cluttonfred
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    cluttonfred Junior Member

    Old thread but this is a boat that still fascinates me. I have some Don Elliott comments and drawings on this design going back about 20 years that I will try to pull together. In the meantime, since some of the links in this thread are long dead, here is Bolger's original description of this boat from his book Different Boats.
     

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    Last edited: Apr 11, 2021
  11. cluttonfred
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    cluttonfred Junior Member

    The following thoughts and drawings by the late Don Elliott were posted to the Yahoo! Groups "smallboats" list back in 2001 as an analysis of the design and partly in response to Phil Bolger's description and rationale in the PDF I uploaded in my previous post. I am sharing Don's input here so it won't be lost as some of the thoughts are applicable to many other designs as well. Cheers, Matthew

    "Sat Feb 3, 2001 6:49am
    STORM PETREL'S FLOTATION NO. 1

    Let's look at Storm Petrel's flotation.

    Any boat that carries a dense material on board, such as lead, steel or even say a motor should have adequate flotation material on board to prevent the boat from sinking. Wooden boats without dense materials are an entirely different matter; here we are looking at Storm Petrel's flotation.

    The list below is a basic outline of what that flotation should be doing.

    1. It should prevent the boat from sinking.
    2. It should float the boat level.
    3. It should be of the correct amount.
    4. It should be located in the right place.
    5. It should be securely fixed.
    6. It should be the right material.
    7. It should allow the boat to be bailed in the case of total flooding.

    I'll bet that most boat builders, and for that matter most boaters give very little thought to flotation. They would undoubtedly think about it right away if they found their self in the situation shown in the sketch below:
    float1.jpg
    In this series of articles we hope to show that is indeed worth thinking about flotation. This article will give you an idea of how flotation is designed into a boat.

    Mr.Bolger designed Storm Petrel with 5 cubic feet of flotation material; he has placed 3 cubic feet aft and two cubic feet forward. Let's look at why he arranged it this way. See the Sketch below for the explanation:
    float2.jpg
    In the top view you can see by placing it high up in the boat, the boat floats at deck level. This position allows the boat to rotate back to the upright position if capsized. Now look at the lower view, the floatation material was not secured solidly and has moved to the bottom of the hull. The boat will still float but will be harder to right, if not impossible.

    Next look at the following sketch and see what will happen if you, for some reason, you decide to relocate the flotation material:
    float3.jpg
    As you can see, this is not a good idea. The boat still floats but it will never right itself from this position.

    In the next article we'll study flotation even more.

    Don"
     
  12. cluttonfred
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    cluttonfred Junior Member

    Don Elliott on Storm Petrel continued

    "Tue Feb 6, 2001 6:57am
    STORM PETREL'S FLOTATION NO 2.

    This article on Storm Petrel will study Mr. Bolger's choice of location for the flotation material aboard Storm Petrel. We will look at what effect its location will have on the boat. We will attempt to find the reason or reasons Mr. Bolger locates it where he has, and then we can determine how much of a value it will be to us.

    If you recall from an earlier article, Storm Petrel will float in the position as shown in the first sketch shown below. It will float at deck level because the flotation material is located high in the boat.
    float1.jpg float2.jpg
    It was pointed out earlier that with the flotation at deck level the boat would quickly right itself if capsized because of this location (see the second sketch, top view). Notice in the sketch showing the flotation at the bottom the boat will not right itself easily or worse not at all,

    Why are we then questioning the location at all? Well not all designers agree on the location of flotation. Some designers* believe that any ballast boat should have all its flotation at the bottom of the boat. Their reasoning is that if the boat is holed the boat will float high in the water as shown in the sketch below (lower view):
    float6.jpg
    The reason they want it to float high is in this position very little water will enter the boat, allowing you to repair or plug the hole and then press on.

    Mr. Bolger states that even with Storm Petrel holed and flooded you will still be able to sail even if it were completed flooded. So, who then is right? Well the answer to that is what do we want the boat to do? That involves more study. Here is a brief list of what we want:

    1. What we want is the flotation material not to encroach on our needed space.
    2. If capsized we want the boat to right itself and not be stuck upside down.
    3. If holed or flooded we want to be able to plug the hole and bail the boat.
    4. We want the boat to be able to sail or motor on in any condition.
    5. We want to correct the problem in the least amount of time or better yet not to have it occur at all.

    Is it possible to have all of these things? That will be the subject of our next article on Storm Petrel.

    *Ref. Dave Gerr's The Nature of Boats.
    Note:
    1. This study is for small ballast boats.
    2. This study does not apply to unballasted boats, which will be studied in a later article."
     
  13. cluttonfred
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    cluttonfred Junior Member

    Don Elliott on Storm Petrel continued....

    "Fri Feb 9, 2001 8:39am
    STORM PETREL'S FLOTATION NO 3

    While cruising in small boats it has been found that a collision is more likely to happen than a capsize, that of course, is with good sailing on your part. Most collisions happen in congested areas and help will generally be close at hand. Other times collisions can occur in open water, in that case you must deal with the problem on your own. As Mr. Bolger points out the likelihood of these things occurring is very slim to none. Here, however we intent to look at any possible condition that might affect small boat safety, no matter how minor.

    Look at the following sketch; a repair patch is being applied to the hull. Notice that a tether line from the crew to the boat is being used (the larger line). Also notice the emergency bag slung around the sailors neck, the materials necessary for the repair came out of that in that bag (This emergency bag and its use will be show in more detail later). You can see the damage to the hull goes a long way towards the rear of the boat. For the Storm Petrel any damage would have to go back far enough back before it would really do any serious damage. The reason is that the main cabin is a totally separate and the bow is somewhat like a crash box that is in cars, it can be crushed and the cabin will still be intact. Notice also that the boat is floating high enough out of the water to allow the repair to be made; this is due to the flotation material being located at the deck level.
    float9.jpg
    What we can do to make Storm Petrel even better is beef up Storm Petrel bow's wet well a little to make it even tougher. First we'll increase the size of the stem, as designed it's 1-1/2" square stock, by the time it's shaped to take the hull sides you wouldn't have much left, so make it bigger. Next we'll add about a cubic foot of foam flotation in the form of flat insulation material. Any foam material that's use on a boat must be protected from the sun or it will breakdown quickly, so we add a thin material over the foam. (Thin aluminum would be good.) We then epoxy fillet the base of that to the hull. Also we have butted the keel mounting doubler up against the stem. Now the bow section is stronger and will absorb a shock or collision far better than the original design. There is another reason for adding flotation in the bow section, which will become clear in the following paragraph. You can see the changes that were made in the following sketch:
    float8.jpg
    If you recall in the last article there was concern that with flotation located at the deck level bailing could be a problem. We will cure this problem in two ways. The first is to add flotation material along the side of the cabin walls the same way as we did in the bow, except in this case no protective panel is required, as it is not exposed to the sun. The addition of the flotation material will now float the boat higher allowing easier bailing and repair, it will also provide thermal insulation. See the sketch below, notice the hull is still in balance:
    float5.jpg
    The second way to raise the boat higher is to add flotation at the bottom of the hull; we can do this by using an inflatable sleeping mattress and a truck inner tube in the cabin. The mattress would be secured to the bottom panel and the inner tube would go under the floor panel. The inner tube would be stored flat and only inflated if needed. The following sketch although it is from a totally different boat but will work equally as well on Storm Petrel:
    lower_level_flotation.jpg
    Now Storm Petrel is a much safer boat it will right itself easily and if damage it will float high in the water. Repairs can be easily made in any situation and the boat will be able to press.

    Don"

    That's the end of the flotation series, I will pull together more another day. I should point out that while I appreciated Don's comments (and I was very jealous of his artistic skills), I didn't necessarily agree with everything he said. Still, there was a lot of food for thought in his posts.

    Cheers,

    Matthew
     
    Last edited: Apr 11, 2021
  14. cluttonfred
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    cluttonfred Junior Member

    Don Elliott on Storm Petrel continued

    "Wed Jan 31, 2001 9:33 am
    STORM PETREL STUDY NO 1

    This article will begin a study of the Storm Petrel as design by Philip Bolger. The Storm Petrel is an excellent boat and as Mr. Bolger points out it's the absolute minimum seaworthy boat. The articles will look at the ideas applied to this design and also see if there are ways to improve the design.

    As Storm Petrel was designed a long time ago some new building method and new design ideas have occurred since that time, so here we'll attempt simply to improve the design and but not change the basic design in any major way.

    In the following sketch we see the keel as designed:
    keel.jpg
    This is what Mr. Bolger says of the keel "Because of the rocker of the bottom offsets the bolt...brace it against side thrust...it strengthens rather than weakens the hull." If you look at the middle view you can see what he means by "it strengthens rather than weakens the hull," any force applied to the boat is resisted by the stiffness of the keel, make the hull actually stronger. An improvement that could be made to that keel is to add an end plate to the lower edge of the keel to prevent water from flowing from the high-pressure side to the low-pressure side while sailing. It would add some drag but the advantage of improving windward sailing might be worth the slight increase in drag.

    In the sketch below we'll look at what might happen if we happen to bend the keel. This may be of some concern to some people however we shall see bending the keel is really not going to endanger the craft at all.
    keel1.jpg
    The view at the left shows the keel attachment to the hull, the drawing is to the exact size of the finished boat. Even with a great force, strong enough to bend the keel you can see that the most that can happen is the mounting tab will deform and nothing more. The reason for this is Mr. Bolger has mounted it with a large 5/8" bolt and backed it with a 7/8" backing block, preventing any movement of that bolt just by its size alone.

    In this next sketch we'll bring the attachment of the keel to the hull up to date with modern materials and also make that attachment far stronger than originally designed.
    keel2.jpg
    To make certain that the attachment will never fail we've added an anti-splitting backing plywood the top of the backing block, this prevents the backing block from splitting. (It is important to select close-grain vertical fir for this block, and run it in the direction shown on the sketch.) We've added a heavy washer and mounted the nut with Lock-tight to prevent any loosening. This nut should be tightened real tight. When Storm Petrel was designed epoxy wasn't in wide use for boat building, we are using here to glue the pieces together. Between the hull and the keel we've added six layers of cloth to give the keel a hard spot to rest on. The hole for the 5/8" bolt must be tight against the bolt, no slop or oversize hole here, it should be tight in that hole.

    To be continued. Don"
     

  15. cluttonfred
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    cluttonfred Junior Member

    Don Elliott on Storm Petrel continued

    "Thu Feb 1, 2001 7:41am
    STORM PETREL STUDY NO 2

    When I first looked at Storm Petrel's hatch I had a couple of reactions. First, it appears as if it was an after thought and just added on at the last moment, I also thought this thing could be blown away easily in the right conditions. Then I thought what would you do with it if you needed to have the hatch off, where would you put it? To store it seems to be a problem, it is to large to fit in the cockpit or the anchor well. What would you do with it? Did Mr. Bolger intend for you to secure it right away after opening it? If the wind was strong enough it could be blown out of your hands and fly overboard. To prevent that you could tie a strong line to it so you could retrieve it but its possible that it could be broken to pieces if smashed around by the strong winds.
    Here's my first thought of how to cure these problems. If you were in the cabin say, although it may be difficult, I believe you have plenty of room to dress without sitting headroom provided by the original hatch cover. So I converted it to a flush deck boat by making a simple low hatch, see the sketch below:

    hatch1.jpg

    The hatch is made secure by nylon hinges and when it's open you can tie it to the mast. The large arrow A indicated that the hatch has been moved forward about a foot forward to allow the crew to sit more in the center of the boat. The spray rail directs fast moving water over the top of the hatch. This hatch set-up would be best for extreme conditions; it allows you to move with greater safety around
    the deck without bumping into the standard hatch cover. If you wanted you could actually have both the tall hatch and the low hatch and use them at different times to suit your trip.

    My second solution was to build a permanent fixed non-removable structure with a hatch at the rear. See the sketch below to see that modification:

    hatch2.jpg

    That hatch would have a nylon hinge and when the hatch was closed it would be secured by a line to a cleat as shown. A compass has been added with an air vent for the cabin, the vent is designed into the compass mounting base. I neglected to show exterior grab handles to the structure, you could use these while moving around on the boat.

    To be continued. Don"
     
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